Internal combustion engine



July 30, 1940. w. LINDNER Er AL :.[NTERNAL COMBUSTION ENGINE 'Filed Nov 418, 1938 2 Sheets-Sheet 1 2 sheets-snee: 2

w. LINDNER Erm.

INTERNAL GOKBUSTION ENGINE nm nov. 1a, 195s July 3o,4 1940.

y/ MW' Patented Julyhsd, 1940 UNITED STATES '2,2091182 x INTERNAL coMBUsv'rioN ENGINE Werner Lindner and Siegfried Grants, Augsburg,

Germany, assignors to Maschinenfabrik Augsburg-Nurnberg A. G., Augsburg, Germany, a corporation of Germany Application November 18, 1938, Serial No. 241,090

In Germany November 24, 1937 Claims.

This inventionV relates to internal combustion engines of the two-cycle character, in which the two-cycle character, in which the exhaust gases are scavenged from the cylinders by a scavenging 5 air flow and carried out through exhaust ports provided in a. side of the cylinder wall.

One object of the invention is the provision of a two-stroke cycle engine ofthe character mentioned having a row of exhaust ports and a row of scavenging air inlet ports arranged below the exhaust ports and on the same side' of the cylinder wall to provide for reverse scavenging iiow from the inlet ports across, along, and back along the cylinder to the exhaust ports, one or more of the exhaust ports being enlarged or len'gthened in a direction towards the inner dead center position of the piston to provide a more eiiicent scavenging action, especially at high speed engine operation.

Another object of the invention is the provision of a two-stroke cycle engine of the character mentioned in which one of the exhaust ports is elongated down to and beyond a transverse plane dening the upper end of the row of inlet ports, the inlet port adjacent such extended exhaust ports having a reduced size compared to an adjacent inlet port.

Other objects and advantages of the invention will be apparent from the following description,-

the appended claims, and the accompanying drawings, in which: v

Fig. 1 is a longitudinal central vertical section through an engine cylinder having a port arrangement embodying the present invention;

35 Fig. 2 is a longitudinal vertical section taken on the line 2--2 of Fig. 1; FiFigl. 3 is a transverse section on the line 3-3 of gi Fig. 4 is a longitudinal vertical section through a cylinder showing a modified port arrangement n which one of the exhaust ports is of trapezoid orm; Fig. 5-is a longitudinal 4vertical section on the line 5-5 of Fig. 4; Fig. 6 is a transverse section on the line 6-6 of Fig. 4; and

y Fig. '7 is a longitudinal vertical section through a cylinder showing another modification of the ports. Referring more particularly tothe drawings by reference numerals, I designates the cylinder oif an internal combustion engine of the two-cycle character. One side of the cylinder wall is provided with a row of scavenging air inlet ports or slots 3, and aboveithe inlet ports 3 is a row (Cl. 12d-65) of exhaust ports l and 5, the inlet and exhaust ports being arranged on the same side of the cylinder wall and opposite an imperforateportion of the cylinder wall to provide a reverse scavenging action when the ports are uncovered 5v by the piston 2, the scavenging ow taking place4 from the inlet ports 3 across the top of the piston, along the cylinder wall towards the cylinder head, under the cylinder head, and -then back alongV the cylinder 'to the exhaust ports. 'I'helo` fuel may be supplied tothe cylinder in any customary manner, for example by means of a fuel injection nozzle 6 provided in the cylinder head, and as such form of fuel injection is common practice the fuel injection nozzle is not illusy15 trated. x

The port arrangement of the present-invention is one in which at least one of the exhaust ports is elongated or .lengthened in the direction towards the lower dead center position of the pis- 20 ton to provide a more eilicient and effective scavenging action; not only because of the increased exhaust area which it provides but also because of a. more thorough removal of the exhaust gases, particularly at high speed engine operation. The 25 greater ow of the exhaust gases through the lelongated port induces a ow of a portion of the scavenging air so as to make-that portion travel upwardly through a part of the combustion space which is removed a substantial distance 30 from the cylinder wall because the exhaust gas core or portion within the cylinder near the enlarged exhaust port is not as'dense as the adjacent portions and-the scavenging. stream or streams closest to this exhaust gas portion is to 35 some extent drawn towards and into it. The core of exhaust gases lying towards the4 center of the combustion, space is-therefore completely scavenged and pushed out ahead-of the scavenging air.

As shown more particularly in Figs. 1, 2 and 3 the upper ends of the exhaust ports are arranged substantially in the same common transverse plane, and quite remote from the cylinder head, one oiA the exhaust, ports, such as the 4,5 exhaust port i. being extended downwardly towards the row of scavengingl air inlet ports 3. 'I'he exhaust port 5, which thus extends downwardly a greater distance than the other exhaust ports adjacent to it, thus provides an ex- 50 haust passage oi considerably greater-areal than the adjacent exhaust ports, causing/a compara.- tively rapid rate of iiow of the exhaust gases. As

/shown here, the extent to which the exhaust port 5 reaches downwardly or towards the lower'dead 56 center position of the piston is such that as the piston descends it will still be uncovering the exhaust slot 5 when it starts to uncover the scavenging air inlet ports 3. The inlet port which is arranged below the port 5 is of reduced height as compared with the inlet ports provided on opposite sides thereof. As will be apparent from Fig. 3, the side walls of the inlet ports are so inclined towards the center of the side of the cylinder opposite the zone in which the ports are arranged to direct the air streams generally towards that center as they enter the combustion chamber, while the lower and upper walls of the scavenging air ports curve downwardly to dirct the scavenging air streams towards the top of the piston.

The scavenging air streams thus flow over the top of the piston'in different paths and then move up towards the cylinder head to provide a reverse scavenging flow out of the exhaust ports. Since the exhaust port 5 is of considerably increased area as compared to the adjacent exhaust ports, the total resistance to flow of the exhaust gases will be reduced, and the increased rate of flow through the enlarged port 5 will induce the scavenging air streams coming in from the immediately adjacent ports to move up substantially towards the cylinder head before traveling very far across the piston head. These upiiowing streams of scavenging air are near the central axis ofthe cylinder and they push the central or core portions of the exhaust gases ahead of it and force this core portion out of the exhaust slots, providing a more eicient scavenging action, especially at high speed engine operation in which the speed of rotation of the engine shaft may be.of the order of 1000 R.. P. M. or more. In accordance with prior' practice, it has been diicult to effectively cleanse all of the burnt gases from the combustion chambers of engines of the two-cycle type operating at high speed because of the very short time in which the. scavenging action must take place in a cycle, although exhaust gas whirlings in the combustion chamber produced by the scavenging air action, and so undesirable because it interferes with the systematic propulsion of the burnt gases ahead of the scavenging air flow, is not excessive in high speed engines. In accordance with the present invention, the increased area. through which-the exhaus, gases can move outof the cylinder prevents the exhaust gases from collecting in front of the outlet openings, and the air streams are so directed in the cylinder as to effectively scavenge the gases from not only the outer portions of the combustion chamber but also to remove the inner core of exhaust gases and propel the same before it during its reverse flow through the combustion space. This increase in eiectiveness of the scavenging action is obtained without arranging the upper ends of the exhaust ports any closer to the cylinder head than is expedient for efiicient action.

The exhaust port which extends to a greater distance towards the lower dead center position of the piston is not necessarily the central slot of the row, and the end slots of the row of exhaust slots may be the ones that are enlarged; and it is unnecessary that a rectangular scavenging air slot be provided below the enlarged exhaust port. As shown in Figs. 4, 5, and 6, the exhaust port 5 is of trapezoid form, extending downwardly toward a point corresponding substantially to the plane which denes the lower end of thescavenging air ports 3, the scavenging air ports which are provided below the outer portions of the enlarged exhaust port 5 being oi considerably reduced cross sectional area and of triangular form as shown in this figure. The smaller streams of scavenging air entering through these smaller inlet ports of triangular form are thus to a certain extent drawn into the zone of the exhaust gas core lying towards the center of the combustion chamber because the exhaust gas core adjacent the enlarged outlet port 5 is naturally less dense than the other portions by reason of the increased rate of iiow of the exhaust gases into this enlarged exhaust port.

In accordance with the construction shown in Fig- 7, the enlarged exhaust port 5 is of rectangular form and projects down towards the piston to the plane dening the lower end of the inlet slots 3 so that the exhaust port 5 will not be fully uncovered until the scavengmg air inlet ports 3 are completely uncovered by the piston. In this case the scavenging air entering the inlet ports 3 immediately adjacent the enlarged port 5 will be drawn towards the center of the cylinder toa substantial degree because of the increased flow of exhaust gases through the larger exhaust port 5.

While the forms of apparatus herein described constitute preferred embodiments of the inven-v tion, it is to be understood that the invention is not limited to these precise forms of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

1. In a two-stroke cycle engine, a cylinder and a piston operable therein, said cylinder having a row of exhaust ports and a row of scavenging air inlet ports arranged below the row of exhaust ports, said exhaust ports and inlet ports being adapted to be uncovered by. the piston and ar-l ranged on only one side of the cylinder opposite an imperforate portion of the cylinder to provide for reverse scavenging flow from the inlet ports across, along, and back along the cylinder to the exhaust ports, at least one of said exhaust ports being closely adjacent an inlet port and extended towards the inner dead center position of the piston to a greater extent than other exhaust ports and at least to the transverse plane dening the upper end of the row of inlet porta.

2. In a two-stroke cycle engine, a cylinder and Va piston operable therein, said cylinder having a row of exhaust ports and a row of scavenging air inlet ports arranged below the row of exhaust ports, said exhaust ports and inlet ports being adapted to be uncovered by the piston and arranged on one side of the cylinder to provide for .reverse scavenging flow from the inlet ports across, along, and back along the cylinder to the exhaust ports, at least one of said exhaust ports being extended towards the inner dead center position of the piston beyond the transverse plane dening the upper end of the row of inlet ports, the inlet port adjacent said extended exhaust port having a reduced size compared to an adjacent inlet port.

3. In a two-stroke cycle engine, a cylinder and a piston operable therein, said cylinder having a row of exhaust ports and a row of scavenging air inlet ports arranged below the row of exhaust ports, said exhaust-ports and inlet ports being adapted to be uncovered by the piston and arranged on one side of the cylinder opposite an across the cylinder, along. the opposite side of the cylinder, and back along the adiacent'side of the cylinder to the exhaust ports, the exhaust port in the middle of the row being closely adjacent a plurality of said inlet ports and extended towards the inner dead center position of the piston to a greater extent than other exhaust ports and to a region where it will not be fully uncovered by the time the piston startsto uncover an inlet port. l

4. In a two-stroke cycle engine, a cylinder and a piston operable therein, saidV cylinder having a row of exhaust ports and a row of scavenging air inlet ports arranged below the row of exhaust ports, said exhaust ports and inlet ports 4being adapted to be uncovered by the piston and arranged on one side of the cylinder opposite an imperforate portion of the cylinder wall to provide for reverse scavenging ow from the inlet ports across, along, and back along the cylinder to the exhaust ports, at leastone of said exhaust ports being extended towards the inner dead cen-'- ter position of the piston beyond the transverse' plane dening the upper end of the row of inlet ports and arranged axially above an inlet port which extends axially ltowards the cylinder head a substantially smaller distance than the inlet port adjacent thereto.

5. In a two-stroke cycle engine, a cylinder and a piston operable therein, said cylinder having a row of exhaust ports and a. row of scavenging -air inlet ports arranged below the row of ex-.

haust ports, said exhaust ports and inlet' ports Vbeing adapted to be uncovered by the piston and arranged on one side of the cylinder opposite an imperforate portion of the cylinder wall to p ro. vide for reverse scavenging ilow from the inlet ports across, along, and back along the cylinder to the exhaust ports, at least one of said exhaust ports being extended towards the innerA dead center position of the piston beyond the transverse plane detlning thepupper end of the row of inlet ports, said extended exhaust port having its lower portion of substantially smaller annular length than its upper portion and arranged above and closely adjacent a plurality of substantially triangular inlet ports which are comparatively small in size as compared to the other inlet ports.

WERNER LINDNER.

CERTIFICATE OF CORRECTION.

Patent No. 2,209,782. July 5o, 191m.

WERNER LINDNER, ET AL.

It is hereby certified that error appearsin the printed specification ofthe above numbered patent requiring correction as follows: Page l, first strike out the words and comma in which the two- Y' read -port and that the said that the same column, lines 2 and 5, cycle character," line 26, for "ports Letters Patent should be read with this correction therein may conform to the record of the ease in the- Patent Office.

. signed and sealed this 27th day of August, A. D. 191m;

Henry Van Arsdale, V

(Seal) Acting Commissioner of Patents. 

